Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/14—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles in several steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B11/00—Making preforms
  • B29B11/06—Making preforms by moulding the material
  • B29B11/12—Compression moulding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/006—Pressing and sintering powders, granules or fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2791/00—Shaping characteristics in general
  • B29C2791/001—Shaping in several steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/06—PE, i.e. polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/25—Solid
  • B29K2105/251—Particles, powder or granules
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/25—Solid
  • B29K2105/253—Preform
  • B29K2105/255—Blocks or tablets

Definitions

• blanks having larger dimensions than those of the finished parts are first produced by mechanical pressure and preferably at room temperature. These blanks are subsequently converted into sintere'd and plasticized polyethylene by the simultaneous use of heat and of mechanical pressure.
• slabs of 20 x 20 centimeters and 3 cm. thickness may first to be produced by cold-pressing. These slabs may be placed side by side into a die of 1 x 2 meters. If at least one additional compression is now applied while heating, one single sheet of 1 x 2 meters and 3 cm. thickness is obtained. Seams are no longer recognizable in the finished sheet. According to another embodiment of the process of the invention, heating of the individual slab is not effected in the second compression stage but previously as, for example, is an oven under a protective gas atmosphere.
• the blanks obtained from the first stage consist of prisms having 6 surfaces positioned at right angles .with respect to one another, or of disks of circular or other form with par allel surfaces.
• the prisms may be arranged side by side in one layer, or the prisms or disks may be placed one upon another. It is advantageous in many cases to place prisms side by side and in layers.
• the process of the invention is also applicable to the production of shaped parts of plasticized polypropylene.
• the process of the invention is primarily applicable to high molecular weight polyethylene, i.e., for example, polyethylenes having molecular weights in excess of 100,- 000 and preferably above 500,000.
• Polyethylene of this type is known as high-density polyethylene and is produced by the polymerization of ethylene at pressures below about 100 kg./ sq. cm. and temperatures up to about 100 C. with the use of catalysts consisting of mixtures of organometallic compounds, especially aluminum alkyl compounds, with compounds of metals of the 4th to 6th subgroups of the periodic table, particularly with titanium compounds as, for example, titanium tetrachloride (see Angewandte Chemie, vol. 67, 541-547 (1955)).
• Example 1 The polymerization of ethylene was effected in a glass vessel of about 5 liters capacity and equipped with an agitator, into which were filled 2 liters of a C -C hydrocarbon fraction obtained by carbon monoxide hydrogenation. This hydrocarbon fraction had been prepared by hydrogenation, eifected at 250 C., subsequent refining with sulfuric acid, and intensive drying. After flushing of the reaction vessel with ethylene gas and heating to about 50 C., the catalyst solution was added while agitating and passing ethylene through the vessel. The catalyst solution had been prepared by mixing together 100 cc. of the same C C fraction, 1.08 grams of diethyl aluminum monochloride and 0.42 gram of titanium tetrachlo ride, and vigorously shaking the mixture for about 30 minutes. Upon addition to the catalyst solution, the reaction temperature was adjusted to about C. Atmospheric pressure prevailed throughout the reaction as glass equipment cannot be subjected to elevated pressures.
• the mixture was filtered and the filter residue was treated with times its quantity of 1% aqueous sodium hydroxyide solution in a stirring flask.
• the mixture was then heated to the boiling point, thereby distilling oil the residue of the hydrocarbon fraction together with the water vapor.
• the residue from the distillation was finally washed to free it from alkali and was then dried.
• the polyethylene obtained had a molecular weight of 1,100,000, as determined viscosimetrically.
• sheets of 100 x 80 cm. were produced by heating the blanks obtained by cold-pressing, in the first compression stage to 160 C. in an oven under a protective gas atmosphere; then the heated slabs were placed side by side into the preheated die of 100 X 80 cm. and compressed in a press which was not heated, or only slightly heated.
• sheets having the same good properties were obtained.
• Example 2 Polyethylene as prepared in Example 1, i.e. having a molecular weight of 1,100,000 as determined viscosimetrically, was used in this example, too. 38 kg. of this material, in a die of 50 cm. in width and 80 cm. in length, were cold-pressed at a specific pressure of 130 kg./ sq. cm. This resulted in blanks of 14.2 cm. in thickness.
• the cold-pressed blanks were compressed into sheets in a heatable press for about 8 hours and at a temperature of 160 C.
• the sheets, whfie hot, were subsequently placed one upon another and compressed for about minutes under a specific pressure of 18 kg./ sq. cm. with no additional supply of heat.
• a block of polyethylene was obtained having a weight of 152 kg. and a size of 50 x 80 x 32 The block was completely homogeneous and showed no reduction in strength at the seams.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=7400555

Family Applications (1)

Country Status (6)

Cited By (5)

Citations (8)

Family Cites Families (3)

• 0
  • BE BE561820D patent/BE561820A/xx unknown
  • NL NL100964D patent/NL100964C/xx active
• 1956
  • 1956-11-05 DE DER19942A patent/DE1124225B/de active Pending
• 1957
  • 1957-10-18 GB GB32595/57A patent/GB853194A/en not_active Expired
  • 1957-10-18 FR FR1186391D patent/FR1186391A/fr not_active Expired
  • 1957-11-04 US US694088A patent/US3134830A/en not_active Expired - Lifetime

Patent Citations (8)

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